Pharmacodynamics (ADVERSE DRUG Reactions // Pharmacogenetic Disorders // Drug Allergy)

Question 1

What’s meant by adverse drug reactions ?

Answer 1

The term “Adverse reactions” is used for harmful effect of a drug w require reduction of dose, drug withdrawal or immediate treatment.

Question 2

What are the different types of adverse drug reactions?

Answer 2

Type A: Augmented, Type B: Bizarre, Type C: Continuous, Type D: Delayed, Type E: Ending of use

Question 3

In type A of adverse effects, we have
1. Intolerance when dose is ……… than therapeutic. EX ?
2. Side effect when dose is …….. therapeutic. EX ?
3. Overdose when dose is ………… therapeutic. EX ??
4. Toxic effect when dose is ………. therapeutic. EX ??

Answer 3

1. Intolerance
   - dose is smaller than therapeutic.
   - EX : tinnitus after a single, small dose of Aspirin dose due to lower thrshold to a normal pharmalogical action of drug.
2. Side Effect
   - Dose = Therapeutic.
   - EX :
   *1ST pharmacological Action *: Dry mouth from antihistaminics (as also antagonist on muscarinic receptors affecting salivary glands)
   2RY Pharmacological Action : Thrush 18 (infection of candida) while taking antibiotic.
3. Overdose
   - Dose is larger than therapeutic.
   - Lidocaine => Seizure.
4. Toxic Effect
   - Dose is very high than therapeutic.
   - Hepatotoxicity w/ acetaminophen (paracetamol)

Question 4

In type B, we have :
………… & ………..

+ Explaiantion & EX ?

Answer 4

1. Hypersensitivity
   Immune based adverse reaction, not related to dose bu induced by drugs acting as Ag.
2. Idiosyncrasy
   Genetically mediated adverse effects, effect appears only when drug acts w/ a genetic defect already existing.
   EX : Porphyria & Favism

Question 5

In type C, Adverse effects occur due to …………..
Give EX ?

Answer 5

Chronic use of drugs
EX :
Chronic use of analgesic => nephrotoxicity (Kidney)
Chronic use of Corticosteroids => Osteoporosis (as decrease in Ca absorption => bone weakness), Diabetes, Hypertension (salt & water retention)

Question 6

What are the 3 types of delayed adverse effects of drugs?

Explaination ?

Answer 6

Mutagenicity Drug induces gene abnormalities
, Carcinogenicity Drug-induced neoplasm.
, Teratogenesis Drug-induced fetal abnormality. Occurs when the drug is used during 3-10 weeks during intrauterine life.

Question 7

EX of teratogenic drugs.

Answer 7

Thalidomide Phocomelia
Tetracyclins Dental Hypoplasia
Antiepileptic : cleft palate
I 131 : fetal goiter

Question 8

What is an example of adverse effects following withdrawal of narcotics, alcohol, or hypnotics? + w type of adverse reactions ?

Answer 8

Abstinence syndrome in drug-dependent individuals.
Type E

Question 9

What condition can occur on sudden withdrawal of chronic corticosteroid therapy? w type of adverse reaction ?

Answer 9

Addisonian crisis.
Type E.

Question 10

What can follow the abrupt discontinuation of β-adrenoceptor blockers? why ? w type of adverse reaction ?

Answer 10

Angina or infarction. ///
due to upregulation of β-adrenoceptors → ↑ heart activity ///
type E

Question 11

What can occur on clonidine withdrawal? w type of adverse reaction?

Answer 11

Hypertension and sympathetic over-activity ///
Type E

Question 12

What’s meant by drug abuse ?

Answer 12

Another form of adverse effects caused by using the drug for non therapeutic use inducing independance.

Question 13

What can happen after stopping oral anticoagulants? w type of adverse reaction?

Answer 13

Thromboembolism
(Thromboembolism refers to the formation of a blood clot (thrombus) in a blood vessel, followed by its detachment and movement (embolism) to another location within the circulatory system.) /// Type E

Question 14

What’s meant by Iatrogenic Disease (Drug induced disease)

Answer 14

drug prescribed for a disease causes another disease
EX: Aspirin-iduced Asthma or peptic ulcer
Antipsychotic-induced Parkinsonism.

Question 15

What is Acetylation polymorphism ?

Answer 15

The Population divided into slow and rapid acetylators, drug metabolized by acetylation accumulate in slow acetylators and cause toxic effect than w/ rapid acetyltor.
EX : IN Slow Acetylators, include Isoniazid => neuropathy & Hepatitis.

Question 16

What genetic abnormality causes hemolytic anemia ?

Answer 16

Congenital deficiency of glucose-6-phosphate dehydrogenase (G6PD) enzyme

Question 17

Cause of Respiratory muscle paralysis w/ Apnea following Succynilcholine administration in genetically predisposed patient due to genetic defect in ……………….

Answer 17

Psuedocholine esterase that breaks down succynilcholine.

Question 17

How do RBCs react in the presence of oxidant drugs in individuals with G6PD deficiency?

Answer 17

Readily hemolyzed

Question 18

What is Malignant Hyperthermia ?

Answer 18

Genetic disorder wher skeletal muscle cannot sequester Ca in sarcoplasmic Reticulum following administration of Succynilcholine & Halothane.
=> Muscle regidity & rise in T.

Question 19

What are allergic reactions to drugs mediated by?

Answer 19

Immunogenic mechanisms.

Question 20

Are most drugs complete antigens or haptens?

Answer 20

Haptens.

Question 21

What may occur within a group of chemically related drugs?

Answer 21

Cross-allergy.

Question 21

Is drug allergy dose-dependent or dose-independent?

Answer 21

Dose-independent.

Question 22

What are the chief target organs in drug-induced allergic reactions?

Answer 22

Skin, respiratory tract, GIT, blood & blood vessels.

Question 23

Ex of drug Allergy

Answer 23

Type I (Anaphylactic) :
Penicillin => Athma // Anaphylaxis // Angioedema.
Type II Reaction
Methyldopa => Hemolytic Anemia
Chloramphenicol => Agranulocytosis.

Question 24

Measures Against Allergy

Answer 24

**1. Treatment :
**Epinephrine (in Anaphylactic shock)
Corticosteroid (I.V. Hydrocortisone in Anaphylaxis)
Antihistaminics
**2. Prophylaxis :
**- Cromolyn : Blocks Histamine Release.
- Anti-IgE monoclonal Ab.
- Desensitization or Hyposensitization .

Question 24

Diagnosis of Allergy

Answer 24

1. History & type of Reaction
2. Intradermal & Conjunctival Tests